As such a headup display apparatus for vehicle, the one disclosed in Patent Literature 1 has been known. The headup display apparatus for a vehicle described in Patent Literature 1 is installed inside an instrument panel of a vehicle. The headup apparatus comprises a liquid crystal display (a display) that emits travel information about traveling of a vehicle as display light, a light emitting body (a light emitting device) that is comprised of an LED and arranged adjacent to the liquid crystal display, a printed wiring board provided with a wiring pattern for mounting a light emitting body, a reflection mirror (a reflection member) that reflects display light emitted from a liquid crystal display and output light (illumination light) emitted from a light emitting body, and a unit case (a housing) that houses a liquid crystal display, a light emitting body, a printed wiring board, and a reflection mirror. On the upper end side of the unit case, a translucent part that transmits the display light and output light reflected by the reflection mirror is formed. On the lower end side of the unit case, a printed wiring board provided with a liquid crystal display and a light emitting body is arranged.
According to a headup display apparatus configured as described above, display light emitted from a liquid crystal display and reflected by a reflection mirror and output light emitted from a light emitting body are radiated to a vehicle windshield as a projection member through a translucent part provided in a unit case, and a driver (a vehicle user) visually recognizes a virtual image obtained by the radiation through a windshield.
Further, in this case, a printed wiring board of a headup display apparatus for a vehicle is provided with a control means comprising a microcomputer that operates a liquid crystal display and lights up a light emitting body. Receiving a state signal indicating small amount of fuel remained, for example, such a control means operates a liquid crystal display to display a letter “CHECK” in addition to travel information (vehicle speed display), and at the same time, lights up a light emitting body to display a circular warning indication described later as a part of the virtual image.
Immediately after the liquid crystal display emits the vehicle speed display light and the letter display light “CHECK”, the light emitting body is lit, and the vehicle speed light, the letter display light and the output light emitted from the light emitting body are reflected to the driver through the reflection mirror, the translucent part of the unit case, and the windshield, whereby the driver can view a virtual image comprising the vehicle speed, letter “CHECK” and circular warning indication superimposed on a landscape. The warning indication displayed as a part of the virtual image certainly notifies the driver that the letter “CHECK” is being displayed.